Sound inhibitor and sealing arrangement for water distribution chamber



F 1PM) ()2 1967 R. 1.. UMMEL SOUND INHIBITOR AND SEALING ARRANGEMENT FOR WATER DISTRIBUTION CHAMBER I Filed Feb. 8, 1966 INVENTOR. Richard L. Umme/ H/s Afro/ nay United rates atent ffice SGUND INHIBITOR AND SEALING ARRANGE- MENT FOR WATER DISTRIBUTION CHAMBER Richard L. Ummel, Park Forest, Ill., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Feb. 8, 1966, Ser. No. 534,599 9 Claims. (Cl. 134182) This application is a continuation-in-part of applications Serial No. 450,463, filed April 23, 1965 now abandoned, and Serial No. 332,488, filed December 23, 1963 now abandoned.

This invention relates to a'domestic appliance and more particularly to an improved construction for a dishwashing chamber to prevent the initiation of sound vibrations therewithin.

A desire of the dishwashing art is to obtain an acceptable noise level so that a dishwashing cycle may be operated without disturbing persons in the room. In solving this sound problem, the prior art has placed vinyl coatings on the inside and outside of the dishwashing chamber as well as various sound absorbing materials, such as Fiberglas, in the space between the cabinet and the dishwashing chamber. This invention is directed to a soft coating for the interior of a dishwashing chamber which, rather than absorbing sounds once generated, prevents the initiation thereof due to water impingement on the Walls of the chamber.

Accordingly, it is an object of this invention to provide a combination sound inhibitor and heat insulator for a water distribution chamber.

Another object of this invention is the provision of a soft cushioney plastisol coating on the inside of a dishwashing chamber which prevents the creation of sound vibrations at the point where they would normally originate.

A further object of this invention is the provision of a pervious curtain in taut, spaced relationship to the wall of a water distribution chamber for preventing the generation of sound in said chamber.

It is another object of this invention to provide a soft coating for the inner surfaces of the door and chamber of a water distribution apparatus, thereby to provide a seal where the surfaces meet.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a schematic side sectional view of a dishwasher suitable for use with this invention;

FIGURE 2 is a sectional view taken along line 22 in FIGURE 1 showing a soft sound inhibiting coating adhered to a wall of the dishwasher of a type taught hereinafter in Examples I and III;

FIGURE 3 is a sectional view similar to FIGURE 2 showing a sound inhibiting coating of the type taught hereinafter in Example II;

FIGURE 4 is a sectional view similar to FIGURE 2 showing another sound inhibiting embodiment of this invention: and

FIGURE 5 is a sectional view taken along line 5 in FIGURE 1 showing how a separate seal is eliminated with this invention.

In accordance with this invention and with reference to FIGURE 1, a dishwasher having a top wall 12, a rear panel 14 and a base portion or compartment 16 is adapted to include a dishwashing chamber shown generally at 18. A chamber 18 is a generally box-like receptacle having 3,295,541 Patented Jan. 3, 1967 a depressed bottom defining one portion thereof a sump 20 and a sump outlet 21. An access opening 22 in the front of the dishwashing chamber is adapted to receive a closable dishwasher door 24 in mating sealed relationship therewith as at 23. The door 24 is hinged for pivotal movement about a horizontal hinge in any conventional manner and is adapted to be opened by a door handle 26. Water for the dishwashing process is supplied through a valve 28 in the lower compartment 16.

Although this invention is not limited to a particular type dishwasher, for purposes of illustration, the dishwasher 10 is shown providedwith a spray tube 30 rotatably supported at 32 on a bracket 36 and at 34 on a spray header 42. During a dishwashing cycle, water collecting in sump 20 enters the motor-pump assembly 38 of the type taught in the patent to LaFlame 3,099,992, issued August 6, i963, and is recirculated to the spray tube 30 through a conduit at the back of the dishwashing chamberthe water being so pumped having a swirl inlet into the spray inlet header 42. This swirl imparts a rotational movement to the spray tube 30, thereby causing jets of water to issue from the spray tube ports over the surfaces of the dishes that are carried in conventional support racks, such as 48. Also within the dishwashing chamber 18 is a heater 59 which is energized at the conclusion of the wash portion of the cycle to raise the temperature in the chamber 13 for drying the dishes. The dishwashing cycle and, thus, the pump motor assembly is controlled by a timer 58 which programs sequentially the desired dishwashing cycle.

The pump-motor assembly 38 is of the type which, when the pump is spraying in one direction, recirculates water between the sump and the spray tube 30 and which when rotated in the opposite direction, pumps the soiled wash water to drain through a drain conduit 60.

Noise transmitted outside the dishwasher 10 is created by sound vibrations initiated in the walls such as 12, 14

of the dishwashing chamber 18. These vibrations are created by the impingement of the water from the spray tube 30 hitting the walls of the dishwashing chamber and the subsequent implosion of the water droplets, as well as from air vibrations within the chamber 18 set up by the surging currents of recirculating Water.

Several theories have been advanced for what happens when a flying drop of water hits a hard surface. These theories lead me to believe that water cavitation and the subsequent collapse of the cavity or bubble cause noise in a dishwashing chamber. The first possible explanation of this phenomenon is based on the very rapid radial flow of the water after the water droplet hits. It suggests that when the head of liquid of the drop has just disappeared into radial flow, the continued outward flow of the liquid under its momentum will produce a drop in pressure at the center of the spreading liquid disk. If the pressure at the center of the spreading liquid disk should fall below the vapor pressure of the liquid in question, cavitation may occur. When the cavity collapses, i.e., the bubble implodes, noise occurs.

The second possible explanation of how cavitation conditions may be realized is based on the alternating wave of compression and tension that exists in the head of liquid that has not yet become part of the radial flow of the water droplet. At the first instant of collision a wave of compression, which is initiated by the impact, moves through this head of liquid to the top of the drop. Here it reflects from the free liquid-to-air surface as a tension or negative pressure wave. This negative pressure wave moves back through the drop to the impact surface. It must, in fact, be focused to a very small area of the impact surface by the curvature of the top of the drop in much the same way as ultrasonic waves in water may be focused by a watch glass. The returning negative pressure wave adds algebraically to the compressional wave that is still being initiated at the impact surface as a result of the collision. Since, however, the impact pressure has been decreasing steadily during the time interval in which the first compressional wave front made its round trip through the waterdrop and returned as a negative pressure wave, the net pressure is negative. The extent to which the net pressure is negative depends on the rate of decrease of the impact pressure with time. Here again cavitation conditions may be produced in a liquid drop after collision with a solid surface with the resultant collapse of the bubble giving rise to noise. The prior art attempts to solve this noise problem have been directed only to the absorption of the sound after it is generated. This invention is directed to preventing the very intiation of sound through the use of a foamed coating within the dishwashing chamber.

Turning to FIGURE 2, a fragmentary section of a chamber wall such as 14 is shown comprised of the sheet metal support wall 15 with a cushion layer 62 thereon for stopping sound before it starts. This invention contemplates holding the durometer reading of the cushion layer 62 to a value which will take the energy out of a droplet of water before it strikes a sounding board, such as the metallic panel 15. In other words, the cushion layer is soft enough and thick enough to absorb the energy of a flying droplet of water or an air vibration before either creates a resonance within the dishwashing chamber or, in the case of the water droplet, to prevent the usual cavitation which occurs between the droplet and the layer when the droplet impinges upon the layer. I theorize that the softness of the layer permits it to remain in contact with the water droplet as the droplet first flattens and then subsequently implodes. Without a cavitation in the droplet, the implosion or water rebound will result without an attendant undesirable noise. Following are three examples of processes used to form a satisfactory cushion layer in accordance with this invention, identical reference numerals for the same materials being used where applicable.

Example I.Famed Plastisol Process (FIG URE 2) First step: A plastisol primer 63, such as (XE-13-68- A) comprised of the following materials all parts being by weight:

Weight, percent Copolymer of vinyl chloride and vinyl acetate 11 Bis(3,4-epoxy-6-mcthyl cyclohexylmethyl) adipate 3 Reaction product of 2,2-bis (4-hydroxyphenyl) propane and epichlorohydrin 3 Heat reactive phenol-formaldehyde resin 4 Solvent mixture of: Methyl ethyl ketone (40%),

methyl isobutyl ketone (19%), toluene (20%) 79 and supplied by the Protective Treatments Division of Helen Curtis Corporation, is sprayed on the inside chamber walls to a 0.0005 inch thickness forming a surface to which the foamed plastisol can adhere. A single coat thickness is suificient and a similar coating can also be sprayed, if desired, on the outside of the panel 15 as a rust inhibitor or as a base for finish painting the outside of the chamber.

Second step: Apply, as by spraying or flow coating, foaming plastisol 64 over the primer to an uncured thickness of 1 inch. This is the thickness which normally adheres to the walls of the chamber when the chamber is flow coated and allowed to drain. Such foaming plastisol maybe obtained by exposing vinyl plastisol of the type providing solid coatings to a gas release process. More particularly, plastisol comprised of vinyls and plasticizers, the latter in an amount to produce the desired hardness of the foam, is mixed with enough volatiles to make the mixture liquid. Then the liquid mixture is exposed to a gas release process to impregnate the mix- 4 ture with bubbles, thereby creating the foaming plastisol which, as it dries, will lose the volatile matter to become a plastisol foamthe bubbles remaining as voids in the foam after the gas has escaped. Although the cushion layer 62 in this process is created primarily by the bubbles in the foam, the hardness of the foam layer should be in the range of 45-50 durometers (shore A). Third step: Spray a top coat or skin 65 of organisol, such as (XE-13-66-C) comprised of the following materials all parts being by weight:

Weight, percent Polyvinyl chloride resin 35 Plasticizer of cpoxidized soybean oil and butyl ethylhexyl phthalate 30 CaCO (Filler) 18 TiO (Pigment) 2 Solvent mixture of: Ethyl alcohol (5%), Naphtha Hydrocrabon having a boiling point of 3l0360 F. (10%) 15 and supplied by the Protective Treatments Division of Helene Curtis Corporation, to an uncured thickness of ,6 inch. Then cure the composite for thirty minutes at 300 F.

Example lI.Tw0-Step Solid Plastisol Coating (FIGURE 3 A sufiiciently soft unfoamed coating or layer 162 without a top coat or skin will also prevent the initiation of sound vibration in a water distribution chamber, if the layer has a hardness rating of approximately forty-five durometers (shore A) and is formed as follows:

First step: A plastisol primer 63, such as (XE-1348- A) as identified in Example I above, and supplied by the Protective Treatments Division of Helene Curtis Corporation, is sprayed on the inside chamber walls to a 0.0005 inch thickness forming a surface to which the plastisol can adhere. A single coat thickness is sufficient and a similar coating can also be sprayed on the outside of the chamber as a rust inhibitor or as a base for finish painting.

Second step: Flow coat plastisol 164, such as (XE- 13-66-A) comprised of the following materials all being by weight:

Weight, percent Polyvinyl chloride resin 35 Plasticizer of epoxidized soybean oil and butyl ethylhexyl phthalate 40 CaCO (Filler) 25 Example III.Three-S!cp Solid Plastisol Coating (FIGURE 2 The following process will provide a composite layer with a top coat or skin, said layer having a hardness rating of thirty-five durometers (shore A) which is satisfactory to prevent the initiation of sound. The Example 111 layer is similar to the Example 1 layer 62 except for the use of a solid type plastisol in place of the foam plastisol 64.

First step: A plastisol primer 63, such as (XEl3-68- A) as identified in Example I above, and supplied by the Protective Treatments Division of Helene Curtis Corporation, is sprayed on the inside chamber walls to a 0.0005 inch thickness forming a surface to which the plastisol can adhere. A single coat thickness is sufficient and a similar coating can also be sprayed on the outside of the chamber as a rust inhibitor or as a base for finish painting.

Second step: Flow coat plastisol, such as (XE13- 60-D) comprised of the following materials all parts being by weight:

Weight, percent Polyvinyl chloride resin 25 Plasticizer of epoxidized soybean oil and butyl ethylhexyl phthalate 40 CaCO (Filler) 35 and supplied by the Protective Treatments Division of Helene Curtis Corporation, to an uncured thickness of inch. This plastisol should have sufiicient plasticizers to produce a coating having a durometer reading of thirty-five (shore A). Partially cure the composite coating obtained in steps 1 and 2 for five muintes at 250 F.

Third step: Spray 21 top coating or skin 65 of organisol (XEl3-66C) as identified in Example I above, and supplied by the Protective Treatments Division of Helene Curtis Corporation, and cure the composite layer first for five minutes at 250 F. followed by an additional cure of thirty minutes at 300 F. to 325 F.

Of the layers provided by the foregoing three examples, the preferred layer is the two-step solid plastisol coating 162 shown in FIGURE 3. Note that the durometer (shore A) rating of the layer 162 formed by the two-step process is forty-five, whereas the durometer rating of the three step process in Example III is 35. The additional hardness of the Example II layer 162 compensates for the fact that this layer lacks a top coating or skin. The Example II layer 162 has a smooth but rather dull surface and is the least expensive of the three example layers. The three-step solid plastisol coating of Example III has the best appearance since the top coating has a higher gloss than that obtained with the two-step coating. The layer formed by the three-step process is more durable than the foamed plastisol layer 62 but less durable than the solid plastisol coating 162 of the two-step process.

The foregoing coatings of Examples I, II and III have a total composite thickness in the range of inch to Ms inch, a hardness rating in the range of 35-50 durometers (shore A), and should be used on all interior surfaces of the dishwasher chamber, including the chamber door. The softness of the foregoing coatings will be effective to prevent the production of sound within the dishwashing chamber and, thus, the absorption of sound is made unnecessary.

An additional facet of this invention involves the elimination of a separate door seal through the use of soft mating panel coatings between the door of the dishwasher and the surrounding chamber walls, such as at 23 (FIG- URES l and 5). Since the layers are thicker and softer than that used in the prior art, the need for a separate seal is eliminated. Thus, the novel soft layers of this invention provide not only sound prevention in a water distribution apparatus but the means for sealing around the access opening thereto.

Another embodiment of this invention is shown in FIGURE 4 wherein a wall 66 of a dishwashing chamber 18 is shown in spaced relationship to a curtain 68 hanging adjacent thereto. The curtain 68 may be of nylon mesh, a pervious foam sheeting or a metal screen. In any event, the spaced curtain 68 will break up flying droplets into minute spray particles and cushion the transmission of air vibrations to the chamber panel 66, thereby preventing the initiation of sounds in the structural members of the chamber.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In combination, wall means defining a liquid distribution chamber and having one portion thereof forming an access opening to said chamber, means forming an access door movable into mating sealed relationship with said one portionfor closing said access opening, said one portion of said wall means having one side thereof facing toward said chamber and another side thereof facing toward said access door, means for distributing liquid throughout said chamber and toward impinging contact with said wall means and said access door, said access door having an edge portion adjacent the said other side of said one portion of said wall means when said access opening is closed by said access door, and coating means formed in place on said one side of said one portion of said wall means to intercept said liquid before impinging contact is made with said one portion, said coating means also being formed in place on the said other side of said one portion of said wall means to form one half of a door seal between said access door and said one portion of said wall means, said coating means being formed in place on said access door to intercept said liquid before impinging contact is made with said access door and extending onto said edge portion to form the other half of said door seal whereby a liquid seal is formed between the coating means on the said other side of said one portion of said wall means and the coating means on the edge portion of said access door when said access opening is closed by said access door, said coating means comprising a soft layer having a hardness rating in the range of 35 to 50 durometers (shore A) and a thickness in the range of inch to inch to absorb the energy of a flying droplet of said liquid before impinging contact is made with said wall means, and said coating means being thicker than said wall means.

2. The combination of claim 1 wherein said soft layer comprises cured yieldable plastisol.

3. The combination of claim 2 wherein said soft cured yieldable plastisol layer comprises a foamed plastisol having a skin of organisol covering said foamed plastisol.

4. The combination of claim 2 wherein said soft cured yieldable plastisol layer comprises a solid plastisol.

5. The combination of claim2 wherein said soft cured yieldable plastisol layer comprises a solid plastisol having a skin of organisol covering said solid plastisol.

6. In combination, wall means defining a liquid distribution chamber for washing dishes or the like, means for supplying liquid to said chamber including spray means for said chamber operable for distributing said liquid throughout said chamber and toward impinging contact with said wall means, and coating means on one side of said wall means toward the liquid being distributed to intercept said liquid before impinging contact is made with said wall means, said coating means comprising a soft layer of cured yieldable plastisol having a hardness rating in the range of 35 to 50 durometers (shore A) and a thickness in the range of inch to A; inch to absorb the energy of a flying droplet of said liquid before impinging contact is made with said Wall means, and said coating means extending substantially over all the exposed inner surfaces of said wall means and being thicker than said wall means.

7. The combination as defined in claim 6 wherein the coating means comprises a soft cured foamed yieldable plastisol coating having a hardness rating of about 45 and having a skin of organisol covering said foamed plastisol coating, said foamed plastisol coating being substantially thicker than said skin of organisol.

8. The combination as defined in claim 6 wherein said coating means comprises a soft cured yieldable solid plastisol layer having a hardness of about 45.

9. The combination as defined in claim 6 wherein the coating means comprises a soft cured yieldable solid plastisol layer having a hardness of about 35 which is 7 8 provided with a skin of organisol covering said solid 3,115,885 12/1963 Jenkins 134-176 plastisol layer. 3,194,793 7/1965 Kogon 117-132 X References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 5 810,505 3/1959 Great Britain.

1,348,082 7/1920 Brockhaus 181-33.9 923,207 4/ 1963 Bummiggigg Z332 fig f wig; CHARLES A. WILMUTH, Primary Examiner. 2,846,020 8/1958 Crowley 181-339 R. L. BLEUTIGE,Assistant Examiner.

2,956,915 10/1960 Korn et a1. 220-64 

6. IN COMBINATION, WALL MEANS DEFINING A LIQUID DISTRIBUTION CHAMBER FOR WASHING DISHES OR THE LIKE, MEANS FOR SUPPLYING LIQUID TO SAID CHAMBER INCLUDING SPRAY MEANS FOR SAID CHAMBER OPERABLE FOR DISTRIBUTING SAID LIQUID THROUGHOUT SAID CHAMBER AND TOWARD IMPINGING CONTACT WITH SAID WALL MEANS, AND COATING MEANS ON ONE SIDE OF SAID WALL MEANS TOWARD THE LIQUID BEING DISTRIBUTED TO INTERCEPT SAID LIQUID BEFORE IMPINGING CONTACT IS MADE WITH SAID WALL MEANS, SAID COATING MEANS COMPRISING A SOFT LAYER OF CURED YIELDABLE PLASTISOL HAVING A HARDNESS RATING IN THE RANGE OF 35 TO 50 DUROMETERS (SHORE A) AND A THICKNESS IN THE RANGE OF 1/16 INCH TO 1/8 INCH TO ABSORB THE ENERGY OF A FLYING DROPLET OF SAID LIQUID BEFORE IMPINGING CONTACT IS MADE WITH SAID WALL MEANS, AND SAID COATING MEANS EXTENDING SUBSTANTIALLY OVER ALL THE EXPOSED INNER SURFACES OF SAID WALL MEANS AND BEING THICKER THAN SAID WALL MEANS. 